gaze-following and recognizing intentions from gaze
Outline • infant gaze following studies and intentionality • gaze following and object processing
Do infants gaze-follow? • Infants turn in the direction that an adult has turned. • What is the mechanism underlying this behavior? • The infant notices the head motion and swings her head to the correct half of space without processing adults gaze to an object • The infant follow the gaze and has an understanding about the relationship between the
eyes open/closed experiment • 12, 14, 18 month old infants • between subject design • conditions: adult’s closed or open eye • Infant’s first target look was categorized as “correct look” (+1) if it aligned with adult’s target and as “incorrect look” (-1) if it didn’t.
10. EYES WIDE SHUT 22 1 tant from the infant, at approximately a 75" angle off midline. There were four trials (two to the left and two to the right in a counterbalanced order), and each trial was 6.5 s in duration. Thus, there were no linguistic or emotional cues as to where to turn, and no sound-localization cues because the targets were silent. The infant's behavior was videotaped and subsequently scored by an observer who remained blind to whether the adult turned with open or closed eyes and the direction of the adult turn. For each trial, an infant's first target look was categorized as a "correct look," when it aligned with the adult's target (+ l), or an "incorrect look," when it aligned with the opposite target (- 1). If infants looked at neither target, they received a score of 0 for "non- looking." As is standard in gaze-following procedures, the looking score was a total of the correct looks, incorrect looks, and non-looks (e.g., Butler, Caron, &Brooks, 2000; Flom, DeAk, Phill, & Pick, 2004; Moore & Corkum, 1998). Thus, if an infant consistently looks at correct targets, she would have a posi- tive score (with a maximum of 4), but if she frequently looks at incorrect tar- gets, her score would be negative (with a minimum of -4). The main findings are shown in Figure 10-1. Infants at all ages looked significantly more often at the target when the adult turned with open than with closed eyes. We also scored other behaviors beyond the traditional look- ing measure. We scored infants' average duration of correct looks. This re- vealed that infants inspected the target longer when the adult turned to it with main results open versus closed eyes. Also, more infants vocalized toward the correct tar- get in the open-eyes than closed-eyes condition. Finally, significantly more Open Eyes Closed Eyes All Ages 12mo. 14mo. 18mo. Infants look at the correct target more often in the open-eyes than the FIGURE 10-1. closed-eyes condition. (From Brooks & Meltzoff, 2002. Reprinted with permission of the American Psychological Association.)
other findings • infants inspected the target longer in open- eyes condition. • more infants vocalized toward the correct target in the open-eyes than closed-eyes condition. • significantly more infants pointed to the targets in open-eyes that closed-eyes condition. (interpreted as evidence of “proto-declarative” pointing)
Is closed-eyes condition disruptive? • The adult's eyes were shut only slightly longer than the blink of an eye (half a second) before the turning toward the object for a 6.5 s response period. • no detectable difference in the emotional reactions as a function of condition • The duration measures the length of looking after the infant has turned to the correct target. • Infants show other target-directed acts (pointing at the target and vocalizing toward it) when the adult can see the target.
10. EYES WIDE SHUT 225 A METAMORPHOSIS IN GAZE-FOLLOWING IN INFANCY Rationale The previous study showed that 12-month-olds gaze follow. The question re- mains as to when does this begin? The Gaze-Following: Eyes OpenIClosed test provides a tool for looking at the ontogenesis of gaze-following before the child's first birthday. Brooks and Meltzoff (2005) recently completed a study of infants during the tadpole era, from 9 months to 11 months of age. We used the same proce- dure as previously described, but tested infants within a remarkably controlled age window. The infants were recruited to fall at three discrete ages: 9, 10, and 11 months old, with each infant + 1 week of the target age. This was the equivalent of a cross-sectional microgenetic study-we assessed infants at three moments over a 90-day growth period to see if we could capture a meta- morphosis in behavior. Empirical Findings and Interpretation As shown in Figure 10-3, 9-month-olds did not discriminate between the open- versus closed-eyes conditions. They turned equally often in both cases. However, there was a clear developmental shift 30 days later. For 10-month- When does this begin? olds, the looking scores in the open-eyes condition were significantly greater than in the closed-eyes condition; and a similar significant effect was also evi- dent among l l-month-olds. We also analyzed whether infants vocalized while looking at the correct target, categorized as a "correct gaze + simultaneous vocalization." (Infants Open Eyes Closed Eyes FIGURE 10-3. At 9 months of age infants turn indiscriminately • The same procedure to the target, whether or not the adult can see it. But at 10 and was used for 9 to 11 11 months old, they selectively month old infants. follow the gaze of the adult in the open-eyes condition. Note the sharp decline in looking when the adult cannot see the target (eyes closed). (From Brooks & Melt- 9 10 11 zoff, 2005. Reprinted with permis- Age in Months sion of Blackwell Publishing.)
What could the results for 9-month-old mean? • they are limited to tracking adult’s head movements and run into object by chance. (Butterworth) • They are conditioned to the head movements as a signal for seeing an object on the periphery. (Moore) • They are body-orientation followers. (Melrzoff's "Like Me" hypothesis) body
biological vs physical occluders • 12, 14, 18 month old infants • conditions : headband, blindfold • 14 and 18 month old infants looked at the adult’s target significantly more often in the headband than in the blindfold condition. • The 12 month old didn’t distinguish between conditions.
intervention experiment • Infants randomly assigned to a baseline condition, or two treatment groups : blindfolds, and the same cloth with an opening cut in the middle of it. • The blindfold group experienced that the blindfold blocks their view. • Those infants now interpreted the blindfold correctly. (like-me hypothesis?)
Does gaze-following behavior at 10-11 months predict later language development? • Infants who produced the correct gaze and simultaneous vocalization act at 10-11 months had larger receptive vocabulary at 18 months. • They also built significantly more complex sentences and had larger productive vocabulary at 24 months.
summary • Gaze following happens in 10-11th month of infants development. • Infants come to understand nonbiological occluders to vision sometime around or soon after 1 year of age depending upon the nature of the occluder. • Gaze-following behavior at 10-11 months predicts later language development.
gaze following and object processing • From gaze of others we get information about both ‘inside’ and ‘outside’. (e.g. intentions and mental state vs information about relevant events in the environment) • Is it possible to integrate the two groups? • object properties
motor properties
emotional properties • Do we prefer objects that are looked at by other people? Fig. 1. Illustration of an experimental trial. Here, the face looks left (Box 3), validly cueing the eventual
emotional properties
status properties • Does an object looked at by others look more familiar? Fig . 1. Schematic of stimuli. (A) Direct gaze; (B) eye movement (C) final gaze; (D) central attractor and (E) presentation of two objects.
status properties
beyond an attentional shift • experiments with Experiment 1 – Gaze Cue Experiment 2 – Arrow Cue 6 6 symbolic cues, like Congruent Congruent Incongruent Incongruent arrows, do not guarantee a 5 5 Average Rating Average Rating consequence on object processing. (e.g. no modulation observed in 4 4 affective response to objects using arrow 3 3 cues)
beyond an attentional shift • Non-intentional gaze does not produce the same effects : • fixating on the target and not looking at a distractor • looking away
beyond an attentional shift • The properties discussed seem to persist even when the gaze of others is no longer visible.
Summary • Studies discussed suggest that gaze of others modifies properties of objects and influences object processing: • object gazed at become graspable, attractive and familiar. • These properties are likely to be a product of intentionality of the gaze.
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